Hydrodynamics of Coarse Coal Slime and Quartz Particles in a Liquid-Solid Fluidized Bed Separator

2011 ◽  
Vol 279 ◽  
pp. 350-355 ◽  
Author(s):  
Jie Sha ◽  
Guang Yuan Xie ◽  
Yao Li Peng ◽  
Ben Xuan Shi
Keyword(s):  
Fluidized Bed ◽  
Water Velocity ◽  
Bed Height ◽  
Minimum Fluidization ◽  
Experimental Parameters ◽  
Coal Slime ◽  
Bed Expansion

The hydrodynamics of particles of coarse coal slime and quartz of different sizes in a liquid-solid fluidized bed separator were investigated experimentally, including minimum fluidization velocities, bed expansion ratios, and segregation of mixed particles with two methods. Experimental parameters studied included density and size of particle, superficial water velocity and initial static bed height. The results provide a reference for choice of size scope on coarse coal slime separation by liquid-solid fluidized bed separators.

scholarly journals Study on Fluidization Characteristics of Magnetically Fluidized Beds for Microfine Particles

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 61
Author(s):  
Yakun Tian ◽  
Shulei Song ◽  
Xuan Xu ◽  
Xinyu Wei ◽  
Shanwen Yan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Fluidized Bed ◽  
Magnetic Field Strength ◽  
Fluidized Beds ◽  
Expansion Rate ◽  
Gas Velocity ◽  
Bed Height ◽  
Bed Expansion ◽  
The Magnetic Field

The bed pressure drop, minimum fluidized gas velocity, bed density, and bed expansion rate are important parameters characterizing the fluidization characteristics of gas-solid fluidized beds. By analyzing these parameters, the advantages and disadvantages of the fluidization state can be known. In this study, experiments were conducted to study the fluidization characteristics of a gas-solid magnetically fluidized bed for microfine particles by changing the magnetic field strength, magnetic field addition sequence, and static bed height. The experimental results show that when the magnetic field strength increased from 0 KA/m to 5 KA/m, the minimum fluidized gas velocity of particles increased from 4.42 cm/s to 10.32 cm/s, while the bed pressure drop first increased and then decreased. When the magnetic field strength is less than 3.4 KA/m, the microfine particles in the bed are mainly acted on by the airflow; while when the magnetic field strength is greater than 3.4 KA/m, the microfine particles are mainly dominated by the magnetic field. The magnetic field addition sequence affects the fluidization quality of microfine particles. The fluidized bed with ‘adding magnetic field first’ shows a more stable fluidization state than ‘adding magnetic field later’. Increasing of the static bed height reduces the bed expansion rate. The bed expansion rate is up to 112.5% at a static bed height of h0 = 40 mm and H = 5 KA/m. This will broaden the range of density regulation of a single magnetic particle and lay the advantage of gas-solid magnetically fluidized bed for microfine particles in the field of separation of fine coal.

Bed Height Effects on Fluidized Bed Hydrodynamics

2010 ◽  
Author(s):  
David R. Escudero ◽  
Theodore J. Heindel
Keyword(s):  
Fluidized Bed ◽  
Experimental Studies ◽  
Gas Holdup ◽  
Minimum Fluidization Velocity ◽  
Non Invasive ◽  
Fluidization Velocity ◽  
Bed Height ◽  
Minimum Fluidization ◽  
Imaging Results ◽  
X Ray Computed

Characterizing the hydrodynamics of a fluidized bed is of vital importance to understand the behavior of these multiphase flow systems. Minimum fluidization velocity and gas holdup are two important factors used to understand the hydrodynamics of a fluidized bed. Experimental studies on the effects of bed height on the minimum fluidization velocity and gas holdup were carried out using a 10.2 cm diameter cylindrical fluidized bed filled with 500–600 μm glass beads. In this study, four different bed height-to-diameter ratios were used: H/D = 0.5, 1, 1.5, and 2. Minimum fluidization velocity was determined for each H/D ratio using pressure drop measurements. Local time-average gas holdup was determined using non-invasive X-ray computed tomography imaging. Results show that minimum fluidization velocity is not affected by the change in bed height, while local gas holdup does appear to be affected by the change in bed height.

Particles segregation in fluidized bed binary systems

1986 ◽  
Vol 51 (8) ◽  
pp. 1618-1627 ◽  
Author(s):  
Milan Čársky ◽  
Václav Veselý ◽  
Jaroslav Pata
Keyword(s):  
Binary System ◽  
Fluidized Bed ◽  
Concentration Profile ◽  
Binary Systems ◽  
Equilibrium Concentration ◽  
Critical Limit ◽  
Bed Height ◽  
Minimum Fluidization ◽  
System Equilibrium ◽  
Size Of Particles

Binary systems have been divided into six groups according to their minimum fluidization velocities, densities, and size of particles. A concentration profile of fluidized bed has been studied. Experimental results have indicated that interval (45 - 90 sec.) is necessary for concentration profile generation. The profile appears to be uninfluenced by original arrangement of system components, the composition of bulk and grid region being in mutual equilibrium. Superficial velocity strongly affects system equilibrium, especially at higher jetsam concentrations. The best segregation of the system was achieved at velocities close to the minimum fluidization velocity of the binary system. The binary systems of the 3rd and 6th types change from segregated to mixed fluidized bed if gas velocity increases. The binary system of the 1st type was difficult to mix up since flotsam entrained partially if velocity of air was increased. The equilibrium concentration profile was uninfluenced by the size of the equipment - provided fluidized bed height was above a critical limit.

scholarly journals Numerical Studies on Teeter Bed Separator for Particle Separation

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2025
Author(s):  
Xueshuai Zhu ◽  
Junli Liu ◽  
Chao Cao ◽  
Yalin Dong ◽  
Tao Wei
Keyword(s):  
Fluidized Bed ◽  
Mining Industry ◽  
Water Velocity ◽  
Detection Methods ◽  
Operation Conditions ◽  
Numerical Studies ◽  
Coal Particles ◽  
Large Particles ◽  
Bed Expansion ◽  
Selection Of

Teeter Bed Separators (TBS) are liquid–solid fluidized beds that are widely used in separation of coarse particles in coal mining industry. The coal particles settle in the self-generating medium bed resulting in separation according to density. Due to the existence of self-generating medium beds, it is difficult to study the sedimentation of particles in TBS through experiments and detection methods. In the present research, a model was built to investigate the bed expansion characteristics with water velocity based on the Euler–Euler approach, and to investigate the settling of foreign particles through bed based on the Euler–Lagrange approach in TBS. Results show that the separation of in TBS should be carried out at low water velocity under the condition of stable fluidized bed. Large particles have a high slip velocity, and they are easily flowing through the bed into the light product leading to a mismatch. The importance of self-generating bed on separation of particle with narrow size ranges are clarified. The model provides a way for investigating the separation of particles in a liquid–solid fluidized bed and provides suggestions for the selection of operation conditions in TBS application.

Fluidization Properties and Mixing Properties of Binary Mixtures of Quartz Sand and Coal Char in Fluidized Bed

2014 ◽  
Vol 997 ◽  
pp. 554-559
Author(s):  
Xin Jun Zhao ◽  
Qi Tai Eri ◽  
Qiang Wang
Keyword(s):  
Fluidized Bed ◽  
Quartz Sand ◽  
Volume Fraction ◽  
Coal Char ◽  
Mixing Index ◽  
Mixing Properties ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Bed Height ◽  
Minimum Fluidization

To study the fluidization properties and mixing properties of binary mixtures of quartz sand and coal char, the experiments were carried out in fluidized bed with an inner diameter of 50 mm. The pressure drop lines and mixing index were obtained under different operating conditions with changing the static bed height and the volume fraction of coal char. A new formula of mixing index was proposed to consider the difference of horizontal mixing behavior. The result showed that the static bed height does not make an appreciable influence to minimum fluidization velocity and fluidization status. However, the volume fraction of coal char affected the minimum fluidization velocity obviously, and the minimum fluidization velocity decreased monotonously with decreasing the volume fraction. Although the small volume fraction of coal char was good for mixing, the effect was limited by the height of bed and the mixing index becomes constant almost at 80mm static bed height when the volume fraction was less than 0.4.

Influence of Pressure on Fundamental Characteristics in Gas Fluidized Beds of Coarse Particle

2018 ◽  
Vol 17 (2) ◽  
Author(s):  
Wei Nie ◽  
Libo Dong ◽  
Zhenhua Hao ◽  
Zhonghu Cheng
Keyword(s):  
High Pressure ◽  
Fluidized Bed ◽  
Coarse Particle ◽  
Operating Pressure ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Gas Fluidized Beds ◽  
Group B ◽  
Bed Expansion

Abstract Experiments were conducted to investigate fluidization fundamentals of coarse particle using nitrogen as the fluidizing gas at high pressure. The particle under study was falling in Geldart’s group B/D. A 60-mm-dia. cylindrical Perspex model, a two-dimensional jetting fluidized bed, a 200-mm-semicircular jetting fluidized bed and a 200-mm-dia. cylindrical bed were used in the experiments. The fundamentals of high pressure fluidization examined in this study include minimum fluidization velocity and bed expansion. Empirical correlations were developed for determining minimum fluidization velocity and bed expansion. With the same excess fluidizing-gas velocity, bed expansion generally increases with the operating pressure, but the influence of pressure on bed expansion becomes weaker at higher pressure.

Pressure Effects on Gas-Solid Fluidized Bed Behavior

2003 ◽  
Vol 1 (1) ◽  
Author(s):  
Igor Sidorenko ◽  
Martin J Rhodes
Keyword(s):  
Fluidized Bed ◽  
Elevated Pressure ◽  
Pressure Effects ◽  
Operating Pressure ◽  
Minimum Fluidization Velocity ◽  
Bubbling Bed ◽  
Minimum Fluidization ◽  
Solids Mixing ◽  
Bed Expansion ◽  
Experimental And Theoretical Studies

The purpose of this paper is to review the state of our knowledge of the effects of operating pressure on the hydrodynamic behavior of fluidized beds. With the development of coal combustion and gasification fluidized bed processes in the early 1970s, many academic and industrial researchers have studied the effect of pressure on fluidized bed behaviour. This review covers experimental and theoretical studies of effects of elevated operating pressure on fluidization, published in the literature before August, 2002.The review begins with the discussion of the effect of pressurized conditions on non-bubbling fluidization and several methods for better prediction of minimum fluidization velocity at elevated pressure are presented. The effects of pressure on non-bubbling bed expansion in the region between minimum fluidization and minimum bubbling velocities are considered and areas of uncertainty or disagreement are highlighted. The influence of pressure on the dynamics of gas bubbles and bubbling bed expansion is described next. In addition to fundamental hydrodynamics of fluidization, bed-to-surface heat transfer, jet penetration, solids mixing and particle entrainment are mentioned.

Comparative Bio-sorption of Cadmium and Nickel Ions from Aqueous Solution onto Fibers of Date Palm using Fluidized Bed Column

2019 ◽  
Vol 70 (5) ◽  
pp. 1507-1512
Author(s):  
Baker M. Abod ◽  
Ramy Mohamed Jebir Al-Alawy ◽  
Firas Hashim Kamar ◽  
Gheorghe Nechifor
Keyword(s):  
Aqueous Solution ◽  
Heavy Metal ◽  
Metal Ions ◽  
Fluidized Bed ◽  
Removal Efficiency ◽  
Heavy Metal Ions ◽  
Date Palm ◽  
Operating Conditions ◽  
Initial Concentration ◽  
Bed Height

The aim of this study is to use the dry fibers of date palm as low-cost biosorbent for the removal of Cd(II), and Ni(II) ions from aqueous solution by fluidized bed column. The effects of many operating conditions such as superficial velocity, static bed height, and initial concentration on the removal efficiency of metal ions were investigated. FTIR analyses clarified that hydroxyl, amine and carboxyl groups could be very effective for bio-sorption of these heavy metal ions. SEM images showed that dry fibers of date palm have a high porosity and that metal ions can be trapped and sorbed into pores. The results show that a bed height of 6 cm, velocity of 1.1Umf and initial concentration for each heavy metal ions of 50 mg/L are most feasible and give high removal efficiency. The fluidized bed reactor was modeled using ideal plug flow and this model was solved numerically by utilizing the MATLAB software for fitting the measured breakthrough results. The breakthrough curves for metal ions gave the order of bio-sorption capacity as follow: Cd(II)]Ni(II).

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